1. Field of the Invention
The present invention relates to a lithographic apparatus and a method for manufacturing a device.
2. Description of the Related Art
A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In that instance, a patterning device, which is alternatively referred to as a mask or a reticle, may be used to generate a circuit pattern to be formed on an individual layer of the IC. This pattern can be transferred onto a target portion (e.g. comprising part of, one, or several dies) on a substrate (e.g. a silicon wafer). Transfer of the pattern is typically via imaging onto a layer of radiation-sensitive material (resist) provided on the substrate. In general, a single substrate will contain a network of adjacent target portions that are successively patterned. Known lithographic apparatus include steppers, in which each target portion is irradiated by exposing an entire pattern onto the target portion at one time, and scanners, in which each target portion is irradiated by scanning the pattern through a radiation beam in a given direction (the “scanning” direction) while synchronously scanning the substrate parallel or anti-parallel to this direction. It is also possible to transfer the pattern from the patterning device to the substrate by imprinting the pattern onto the substrate.
In the apparatus, during use, background plasma can be present. For example, during use, the radiation beam traversing a low pressure interior space of the lithographic apparatus can lead to local plasma generation, particularly, in case the radiation is EUV (Extreme Ultra Violet) radiation. Also, for example, the apparatus can comprise a plasma radiation source, to provide the radiation, wherein a small amount of plasma may escape from the radiation source, towards optical components in the lithographic apparatus.
One or more of such background plasmas can impair operation of optical components of the lithographic apparatus. For example, the background plasma can lead to sputtering of optical surfaces nearby optical components, in the case that accelerated plasma particles at least achieve a certain sputtering threshold (kinetic) energy.
WO 2005/064401 describes an apparatus, comprising a debris-mitigation system that mitigates debris particles, for example charged particles, during use of the apparatus. The debris-mitigation system is arranged to apply a magnetic field so that at least charged debris particles are mitigated. The magnetic field can bring electrons (and other charged particles) into a spiraling movement.